Teaming up with means collaborating with others towards a common goal or objective. Some antonyms for this phrase can be working alone, going solo, operating independently, or acting solo. These words signify that an individual is doing something alone or without the help of others. Other antonyms could be going against, opposing, fighting, or competing with someone. These words suggest the opposite of collaborating and imply a sense of conflict or competition. It's important to understand the nuances of antonyms, as they can help you to convey your message more effectively and clearly. Consider the tone and context in which you use antonyms, as this will impact how your words are received.